Phase Transformations in MgH 2 –TiH 2 Hydrogen Storage System by High-Pressure Torsion Process

Kouki Kitabayashi, Kaveh Edalati, Haiwen Li, Etsuo Akiba, Zenji Horita

Research output: Contribution to journalArticle

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Abstract

Magnesium hydride (MgH 2 ) and titanium hydride (TiH 2 ) are two potential candidates for solid-state hydrogen storage, but strong hydride formation energy in these hydrides undesirably results in their high dehydrogenation temperature. First-principles calculations show that the metastable hydrides in the MgH 2 –TiH 2 system have low hydrogen binding energy, which makes them more appropriate for low-temperature hydrogen storage. In this study, severe plastic deformation (SPD) via the high-pressure torsion (HPT) method is applied to the MgH 2 –TiH 2 system to synthesize metastable hydrides. While MgH 2 transforms to a high-pressure orthorhombic γ phase, TiH 2 does not exhibit any cubic-to-tetragonal phase transformation even by HPT processing at cryogenic temperature. Application of large strains by 400 HPT turns to the immiscible MgH 2 /TiH 2 composite results in atomic-scale mixing and formation of nanostructured ternary Mg–Ti–H hydride with the metastable FCC structure and lower dehydrogenation temperature than TiH 2 .

Original languageEnglish
Article number1900027
JournalAdvanced Engineering Materials
DOIs
Publication statusPublished - Jan 1 2019

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Hydrogen storage
Hydrides
Torsional stress
hydrides
torsion
phase transformations
Phase transitions
hydrogen
Dehydrogenation
dehydrogenation
Temperature
energy of formation
cryogenic temperature
Titanium
Binding energy
Cryogenics
Magnesium
plastic deformation
magnesium
Hydrogen

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Phase Transformations in MgH 2 –TiH 2 Hydrogen Storage System by High-Pressure Torsion Process . / Kitabayashi, Kouki; Edalati, Kaveh; Li, Haiwen; Akiba, Etsuo; Horita, Zenji.

In: Advanced Engineering Materials, 01.01.2019.

Research output: Contribution to journalArticle

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